1. Field of the Invention
The present invention relates to a terminal conjugated trienal acetal compound useful as an intermediate for synthesis of an insect sex pheromone and to a method for producing a terminal conjugated trienal compound through deprotection of the terminal conjugated trienal acetal compound.
2. Description of the Related Art
Insect sex pheromones are the biologically active substances which are commonly secreted by female insects and have the function of attracting male insects. A small amount of a sex pheromone shows strong attractive activities. Sex pheromones have been widely used as means for forecasting insect emergence or for ascertaining regional spread (invasion into a specific region) and as means for controlling insect pests. As the means for controlling insect pests, control methods such as mass trapping, lure-and-kill or attract-and-kill, lure-and-infect or attract-and-infect, and mating disruption are widely used in practice. To utilize a sex pheromone, economical production of a required amount of pheromone product is required for basic research and also for application.
Ectomyelois ceratoniae (generic name: Carob moth), which is widely spread in the world and is polyphagous, damages various crops such as nuts and fruits, and thus is an economically serious insect pest. Baker et al. extracted the pheromone glands of Carob moth and found that the sex pheromone thereof was a mixture of (Z,E)-9,11,13-tetradecatrienal, (Z,E)-9,11-tetradecadienal and (Z)-9-tetradecenal at 8:1:1 (Tetrahedron Lett., 30, 2901 (1989)). They synthesized (Z,E)-9,11,13-tetradecatrienal by the method comprising the steps of: Wittig reaction of (E)-2,4-pentadienylidenetriphenylphosphorane with 9-t-butyldimethylsilyloxynonanal, separation of geometric isomers by HPLC, deprotection, and oxidation of a hydroxy group, and confirmed that the above identification had been correct.
Zagatti et al. report that the main component of the sex pheromone of Stenoma cecropia, which is an insect pest causing serious damage to oil palm farms in Colombia, is the same (Z,E)-9,11,13-tetradecatrienal as that of Carob moth (J. Chem. Ecol., 22, 1103 (1996)).
As the other methods for producing (Z,E)-9,11,13-tetradecatrienal, the following two examples are known.
The method of Tellier et al. comprises the steps of: coupling between 10-t-butoxy-1-decyne and 1,2-dibromoethylene, vinylation with a vinyl zinc reagent, reduction of the resulting conjugated dienyne with metallic zinc, deprotection, and oxidation of a hydroxy group (Tetrahedron Lett., 31, 2295 (1990)).
The method of Cabezas et al. comprises the steps of: reduction of the same conjugated dienyne as that in the method of Tellier et al. by hydroboration-protonolysis, deprotection, and oxidation of a hydroxy group (Ingenieria y Ciencia Quimica, 19 (2), 55, (2000)).